1. Field of the Invention
The present invention relates to a liquid droplet ejecting apparatus and a method of controlling the liquid droplet ejecting apparatus.
2. Description of the Related Art
Conventionally, liquid droplet ejecting apparatus that eject ink droplets from nozzles of an inkjet recording head (also called a “recording head” below) to record an image on a recording medium such as recording paper have been known. Usually, the ink is supplied to the recording head via a supply-use flow path from an ink tank in which the ink is stored.
Contaminants such as dirt and dust that become mixed into the ink and air bubbles that form in the ink cause ejection defects and increase flow path resistance, and removing air bubbles and contaminants included in the ink is important for maintaining printing quality.
As an inkjet recording apparatus that includes the function of removing air bubbles and contaminants included in the ink, in Japanese Patent Application Laid-Open Publication (JP-A) No. 2007-223278, there is disclosed an inkjet recording apparatus comprising an ink tank that stores an ink, a pump that pumps the ink stored in the ink tank to a recording head, an intermediate tank that is disposed between the pump and the recording head and includes a flexible bag that stores the ink that has been pumped by the pump, an ink flow path that bypasses the intermediate tank, a plurality of valves that are disposed upstream and downstream of the intermediate tank and in the ink flow path, and a control unit that performs control to open and close the plurality of valves such that the ink is supplied through the intermediate tank or the ink flow path.
However, in the technology disclosed in JP-A No. 2007-223278, there has been the problem that, in the ink supply system that includes the intermediate tank, when the flow path that is communicated with the recording head is pressurized, air bubbles and contaminants included in the ink inside the flow path cannot be sufficiently discharged from the nozzles because, as indicated by graph A in FIG. 13, the pressure acting on the recording head cannot be quickly raised. Further, there has also been the problem that, in the ink supply system including the ink flow path that does not use the intermediate tank, when the flow path that is communicated with the recording head is pressurized, even though the pressure acting on the recording head can be quickly raised, as indicated by graph B in FIG. 13, the pressure quickly falls immediately thereafter, so the flow velocity of the ink inside the flow path is not stable, and air bubbles and contaminants included in the ink inside the flow path cannot be sufficiently discharged from the nozzles.